1. Technical Field
The present invention relates to a memory controlling apparatus of a computer system, and more particularly to a device for protecting a basic input output system (BIOS) stored in a flash-read-only-memory (flash-ROM) of a computer system from malicious computer programs, and a method thereof.
2. Related Art
Computer systems are information handling systems that are utilized by many individuals and businesses today. A computer system can be defined as a microcomputer that includes a central processing unit (CPU), a volatile memory, a non-volatile memory, a display monitor, a keyboard, a mouse, a floppy diskette drive, a compact disc-read only memory (CD-ROM) drive, a modem, a hard disk storage device, and a printer. Typically, a computer system's main board, which is a printed circuit board known as a motherboard, is used to electrically connect these components together.
One example of non-volatile memory is read only memory (ROM). Information stored in non-volatile memory can remain unchanged even when there is a power failure. The information stored in non-volatile memory will stay there until it is changed. Read only memory is used to store important information such as instructions for the central processing unit (CPU). There are different types of read only memory including electrically-erasable-programmable-read-only-memory (EEPROM) chip and flash-read-only-memory (flash-ROM). The flash-ROM can also be referred to as flash memory. There are differences between an EEPROM chip and flash-ROM, as shown below.
Occasionally the important information stored in ROM needs to be updated or modified. When the information to be modified is stored in an EEPROM chip, higher-than-normal voltages are needed in order to erase the contents of the EEPROM chip. Alternatively, when the information to be modified is stored in flash-ROM, the information can be erased and reprogrammed using normal voltages inside a computer. Additionally, in order for information stored on an EEPROM chip to be modified, typically the EEPROM chip must be removed from a computer system, the new information must be stored on the EEPROM chip, and then the EEPROM chip must be reinstalled to the computer system. The flash-ROM is often preferred over the EEPROM chip because no chips need to be removed from the computer system in order to modify information stored in flash-ROM.
Computer systems include a basic input output system (BIOS) which is an especially important program stored in read only memory (ROM). The basic input output system tests a computer every time the computer is powered on. The basic input output system can allocate a computer system's resources automatically, making adjustments needed to accommodate new hardware. Also, the basic input output system governs how system board components interact.
A basic input output system that is stored in flash-read-only-memory (flash-ROM) is vulnerable to computer viruses. Computer viruses include malicious computer programs which can be used to erase information stored in memory. I believe there is a need to provide a method of coping with such malicious programs in order to protect a basic input output system stored in flash-ROM.
Exemplars of recent efforts in the art include U.S. Pat. No. 5,748,940 for a Secure Updating of Non-Volatile Memory issued to Angelo, et al., U.S. Pat. No. 5,550,997 for an in an Interactive Network Board, a Method and Apparatus for Preventing Inadvertent Loading of a Programmable Read Only Memory issued to Ip, et al., U.S. Pat. No. 5,742,935 for a Method and Apparatus for Controlling the Protection Mode of Flash Memory issued to Hazen, et al., and U.S. Pat. No. 5,522,076 for a Computer System Having Bios (Basic Input/output System)-rom (Read Only Memory) Writing Function issued to Dewa, et al.
While these recent efforts provide advantages, I note that they fail to adequately address how a basic input output system (BIOS) stored in flash-read-only-memory (flash-ROM) can be efficiently protected from malicious programs.